Gas generators for safety arrangements usually contain a solid propellent based on sodium azide as the gas-providing main component. Sodium azide is, however, poisonous and can easily become converted with heavy metals forming extremely dangerous and highly reacting compounds. Therefore, both in the production of the gas-generating compositions and also in the disposal of defective or unused gas generators, special measures are necessary.
Furthermore, gas-generating compositions based on nitrogenous organic fuels and inorganic oxidizing agents are known. In the combustion of these compositions, a series of solid substances occur which must be removed from the gas stream by suitable filter arrangements in the gas generator or retained in the gas generator. The use of these compositions requires in addition the use of coated gas bag fabrics in order to prevent damage of the fabric on impingement of hot combustion products. Owing to the high solid content of the reaction products resulting from the combustion of the compositions, the gas yield of these compositions lies distinctly below 80% by weight.
In view of these disadvantages of the known gas-generating compositions, attempts have already been made for the production of propellants which burn substantially smokeless or free of residue. Thus in the U.S. Pat. No. 5,545,272 a gas-generating composition is described which consists substantially of 35 to 55% by weight of nitroguanidine and approximately 45 to 65% by weight of phase-stabilized ammonium nitrate. The addition of phase-stabilizing additives to the ammonium nitrate is considered necessary because a structural change occurring in pure ammonium nitrate at 32.3 degrees C. is connected with an increase in volume which can lead to a fracture of the propellant bodies and hence to an undesired change to the combustion characteristic of the propellant. As phase-stabilizing additives, potassium salts, such as for example potassium nitrate and potassium perchlorate are proposed in a proportion of between 10 to 15% by weight. Ammonium nitrate is, in addition, very hygroscopic, whereby the handling of propellants containing ammonium nitrate is made difficult. The phase changes described above are facilitated also by increased humidity contents.
The U.S. Pat. No. 5,009,728 describes the use of polynitroalkyl compounds as an oxidizing agent in castable, non-sensitive energetic compositions which contain a thermoplastic elastomer as fuel and a plasticizer. One of the polynitroalkyl compounds used as an oxidizer is tetrakis(2,2,2-trinitroethyl)orthocarbonate (TNEOC).
The synthesis of TNEOC is described in U.S. Pat. No. 3,306,939. For this, 2,2,2-trinitroethanol is reacted in the presence of iron(III) chloride with carbon tetrachloride. The various orthoesters of 2,2,2-trinitroethanol described in U.S. Pat. No. 3,306,939 are proposed as a replacement of octogen (HMX) in primary charges of electric igniters. Furthermore, these orthoesters can be used as explosive substances for military applications mixed with trinitrotoluene (TNT).